# set1={'篮球','足球','羽毛球'}
# set2={'羽毛球','乒乓球','游泳'}
# print(set1 & set2)
# # 交集
# print(set1|set2)
# # 并集
# print(set1-set2)
# # 差集





scores={"Alice":85,"Bob":90,"Charlie":78}
# key:value
scores['David']='92'
scores['Alice']='88'

del_score=[]
for name,score in scores.items():
    if score<80:
        del_score.append(name)
for del_ in  del_score:
    del scores[del_]
    print(scores)



